[tex]5x^2+7x-66=0 \\ \\5x^2+7x -22x+ 22x-66=0 \\ \\ 5x^2-15x+ 22x-66=0 \\ \\5x(x-3)+22(x-3)=0 \\ \\ (x-3)(5x+22)=0\\ \\x-3 = 0 \ \ or \ \ 5x+22 =0 \\ \\ x=3 \ \ or \ \ 5x=-22 \ \ /:5 \\ \\x=3 \ \ or \ \ x=-\frac{22}{5} \\ \\x=3 \ \ or \ \ x=-4\frac{2}{5} [/tex]
